In the Note Explorer mode click on the button that displays the name of the current guitar tuning.

 
 
 
 
 
 
 
 
Initial, there is only the Standard guitar tuning in the list. The Standard guitar tuning can not be modified or deleted.
1. Press and hold on the guitar tuining name from the list for opening the context menu of this item.
2. Select the option for editing or deleting this guitar tuning.

 
 
 
 
 
 
 
 
If the editable guitar tuning has been edited or deleted then all the profiles that have used this tuning will be deleted because of their outdated data.